Purchased 100 cords @$5., then purchased 100 cords @3.65 each, sold the last $5. cord, COGS in Products and Services is not changed to $3.65

Hi lilyimportwholes,

Thanks for reaching out. I'm glad to hear you're using the inventory feature in QuickBooks Online to automatically keep track of your asset and costs so you can focus on running your business. I'll be happy to share more on this. 

QuickBooks Online uses an advanced tracking system that follows the First In, First Out (FIFO) concept. This rule allows QuickBooks to consider the first units you purchased to be the first units sold and will adjust your assets and COGS accordingly when you start selling the item purchased at $3.65. The cost field in Product and Services will always display the default price you set up for your item (unless you manually edit it) but rest assured that the FIFO is kicking in accordingly. To visualize how this great process works for you at the back end, I recommend going to your Inventory Valuation Detail report.

To learn more about FIFO and how it works in QuickBooks Online, check out this useful article: What is FIFO and how is it used for inventory cost accounting?

In case you need assistance on how to run a report, here's an article to guide you: Run reports

I hope this helps! Feel free to stop by anytime if you have more questions.